Autolubricating bearing

ABSTRACT

A body of metal (1) provided with a central through passage (2) presenting at least a cylindrical surface (3). A disc (10) is positioned in the cylindrical surface (3). A cylindrical part (12) of synthetic resin is fixed in the body (1), this part (12) presenting an internal cylindrical surface having the shape of a diabolo the medial part of which (13) receives a pivot. The internal frontal face of the part (12) of synthetic resin is in contact with the face of the disc (10).

The present application is a continuation-in-part of mypreviously-copending application Ser. No. 756,090, filed July 17, 1985and now U.S. Pat. No. 4,636,096, Jan. 13, 1987.

The present invention relates to an autolubricating bearingsimultaneously constituting an end abutment which can be used in veryspecial applications imposing extreme working conditions, a total lackof maintenance, a great solidity and a great longevity. These bearingsare particularly intended to equip measuring apparatuses included incontrol panels of airplanes such as artificial horizons, altimeters andbarometers and so on.

For these very particular applications, it is necessary to reduce thedriving torque of the movable parts as much as possible, to ensure agood working in a range of temperature from -60° C. to +80° C., that theworking characteristics be independent of the relative humidity of theenvironment in which the device works.

The bearings which are now used in this type of applications presentgenerally contact surfaces which are provided with graphite so thatduring their storage before the mounting in the instruments andapparatus and during that assembly particular precautions have to betaken to prevent dust from being occluded on the sliding surfaces, whichdamages the working conditions. Further the graphite is sensible to thedegree of humidity so that the characteristics, in particular thedriving torque of the apparatus thus equipped vary as a function of theambiant humidity.

The present invention has the object to provide an autolubricatingbearing avoiding the precited drawbacks and permitting a reduction ofthe driving torque, a greater durability, a total absence ofmaintenance, a perfect working in a range of temperature from -60° C. to+80° C. and which is insensible to humidity.

The autolubricating bearing according to the invention is characterizedin that it comprises a brass body provided with a central throughpassage presenting a first cylindrical surface in which a hard naturalor synthetic stone disc is driven, and a second cylindrical surface, ofgreater diameter than the first one, in which a steel ring is driven,which is provided with a central hole having a diameter less than thatof the first cylindrical surface and one of the annular faces of whichis in contact with one of the faces of the hard stone disc; by the factthat a cylindrical part of synthetic resin is fixed in the steel ring,this part presenting a median internal cylindrical surface intended toreceive a pivot and two conical surfaces widening from that mediancylindrical surface up to the frontal surfaces of that part definingthus a central void having a longitudinal cross section the generalshape of a diabolo, and by the fact that the internal frontal face ofthe part of synthetic resin is in contact with the face of the hardstone disc which is itself in contact with the steel ring.

The attached drawing shows schematically and by way of example twoembodiments of the autolubricating bearing according to the invention.

FIG. 1 is an axial cross section of a first embodiment of the bearing.

FIG. 2 is an axial cross section of a second embodiment of the bearing.

FIG. 3 is a variant of the bearing.

The autolubricating bearing shown on a greatly enlarged scale in FIG. 1has in its actual size an external diameter of about 1 to 3 mm and athickness of about 0.6 to 1.8 mm, that is to say that these bearings areof very small dimensions.

This bearing is intended to equip measuring instruments and apparatusesintended for aeronautics such as altimeters and barometers for example,which have to be insensible to aging, to humidity, to variations oftemperature in a range of -60° C. to +80° C. and which require nomaintenance, lubrication, cleaning or like.

To obtain such a result the material used for the realization of thedifferent parts of the bearing is naturally important, but it is alsonecessary to realize a combination of parts and to determine the shapeof each of these parts so that the characteristics of the realizedbearing be optimal.

The bearing shown in FIG. 1 comprises a body 1 having a generallycylindrical shape, the edges of which have been chamfered to facilitateits assembly in an apparatus or instrument which is generally made byinsertion in a calibrated hole.

This body 1 has a central through passage 2, presenting a firstcylindrical surface 3 and a second cylindrical surface 4, having agreater diameter defining thus a shoulder 5. A third cylindrical surface6 of smaller diameter than the first one 3 defines a second shoulder 7.The ends of the central passage emerging on the frontal faces of thebody 1 are chamfered at 8 respectively 9.

A disc of ruby 10, synthetic or natural, presents a diametercorresponding to that of the first cylindrical surface 3 in order to befixed in the body 1 by driving or by friction in said cylindricalsurface 3. The height h of this disc 10 is equal to the height H of thesaid cylindrical surface 3 so that when the rubis disc 10 is in serviceposition, abutting against the shoulder 7, its other face will belocated in the plane of the shoulder 5. The circular edges of the disc10 are chamfered to facilitate its introduction into the body 1.

It is evident that this disc of rubis 10 could be in variants realizedin an other synthetic or natural stones generally used for industrialbearings.

This disc 10 in hard stone is maintained in service position as shown bya steel ring 11 driven, fitted or fixed in the second cylindricalsurface 4 of the body 1, which rests against the shoulder 5 and whichthus enters into contact with the frontal face of the disc 10. Thecircular internal edges of this ring 11 are chamfered to facilitate itsintroduction into the body 1.

This steel ring 11 houses a part 12 made of a synthetic resindenominated "Hostaform", made by the firm HOECHST AKTIENGESELLSCHAFT,FRANKFURT A/MAIN-HOECHST, with which it is fastened by any means,setting, driving in, gluing etc. The thickness of this part 12 is equalto that of the ring, it presents a central hole 13 of a diametercorresponding to that of a pivot having to cooperate with this bearing.This hole 13 is extended on either side by conical surfaces 14,15widening towards the frontal faces of the part 12. The hollow housing ofthis part 12 has thus in axial cross section the general shape of adiabolo.

This synthetic resin "Hostaform" is autolubricating and does notnecessitate any graphite or any other external lubrication.

Tests made with these bearings have proved that they are very simple toassemble, do not necessitate any lubricating operation, that they needPG,7 no maintenance, that they correspond to the working conditionsrequired and enumerated above and that the driving torque is reduced byabout 50% with respect to a normal bearing and that on top of all thisdriving torque diminishes after a certain time of utilization withoutintroducing any play or other negative consequences. This bearing hasthus mechanical characteristics which improve as a function of itsduration of use.

The second embodiment of the bearing shown in FIG. 2 is a double bearingin which the shoulder 7 against which the disc 10 rests is replaced by asecond ring 11a driven into a cylindrical surface 4a which the body 1apresents and housing a part 12a. Thus, the same disc of hard stone 10 isused as abutment for inline bearings cooperating with two distinctcoaxial pivots. The other elements of this bearing are the same as thosedescribed in reference to FIG. 1.

In variants the design of the bearing can be modified to facilitate itsmanufacturing and reduce its cost.

For example the metallic body 1 can have a through hole of constantdiameter in which the disc 10 as well as the part 12 can be mounteddirectly without the use of a ring 11. Furthermore the inside surface ofrevolution of the autolubricating part 12 can have in cross section thegeneral shape of two curves with opposite curvatures defining a centralarea of minimum diameter.

Finally the disc 10 can also be made in an autolubricating material asthe part 12.

What is claimed is:
 1. An autolubricating bearing, comprising a metallicbody having a central through passage having a cylindrical surface inwhich is disposed a flat disc having flat parallel opposite surfaces,one of said flat surfaces being in abutment with said metallic body andthe other of said flat surfaces forming an abutment for a pivot, and acylindrical member of autolubricating synthetic resin secured in thebody, said member having an internal medial bearing surface adapted toreceive said pivot and two surfaces widening in opposite directions fromsaid medial bearing surface toward frontal surfaces of said member, allof one of said frontal surfaces of said member being in contact withsaid other flat surface of the disc.
 2. An autolubricating bearing asclaimed in claim 1, in which said disc and said member are force fittedinto said body.
 3. An autolubricating bearing as claimed in claim 1, anda metal ring surrounding said member, said metal ring being force fittedinto a cylindrical surface in said body.
 4. An autolubricating bearingas claimed in claim 1, said medial bearing surface being cylindrical. 5.An autolubricating bearing as claimed in claim 1, said medial bearingsurface and said two widening surfaces comprising a continuous smoothcurve.
 6. An autolubricating bearing as claimed in claim 1, both saiddisc and said member being force fitted in the same said cylindricalsurface in said metallic body.